Question: Jessica is 3 times as old as Tiffany and is also 8 years older than Tiffany. How old is Tiffany?
Explanation: We can use the given information to write down two equations that describe the ages of Jessica and Tiffany. Let Jessica's current age be $j$ and Tiffany's current age be $t$ $j = 3t$ $j = t + 8$ Now we have two independent equations, and we can solve for our two unknowns. Since we are looking for $t$ , and both of our equations have $j$ alone on one side, this is a convenient time to use elimination. Subtracting the second equation from the first equation, we get: $0 =$ $3t$ $-$ $ (t + 8)$ which combines the information about $t$ from both of our original equations. Solving for $t$ , we get: $2 t = 8$ $t = 4$.